
is data-driven, i.e., only the input and output data are used. Mathematical physical laws and the associated differential equations are ignored.

is not limited to finite-dimensional linear systems. It has been successfully applied in much more involved situations with nonlinearities and where modeling via partial differential equations has been proposed.Employing PDEs is quite common in the air conditioning of buildings. See, e.g., [1]} and the references therein.

is easy to implement and quite robust with respect to internal and external disturbances, even when compared to the most popular Proportional Integral Derivative controller (see, e.g., [2]});

has already been successfully employed all over the world and gave rise to some patents: see, e.g., the references in [3]}, [4]} and the references therein, and [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}. For obvious reasons let us emphasize here the heating and the humidification of an agricultural greenhouse [12]}, and the heating of a single building [13]}.

